An acute intracranial mass lesion secondary to hemorrhage or edema can lead to profound brain damage or death. Assessment of these patients in the critical care setting is typically done by clinical exam, periodic imaging, and in some cases by intracranial pressure (ICP) monitoring. However, ICP monitoring is invasive and it is not always elevated in patients with ongoing secondary neuronal injury. Perhaps most importantly, it does not provide for direct functional assessment of the brain's status. We propose to fulfill this need by developing technology for real-time objective assessment of brain function at the bedside, using somatosensory evoked potentials (SEP). We have applied traditional amplitude and latency analysis as well as a frequency domain measure, ESPRIT, and demonstrated strong correlation with cerebral perfusion pressure (derived from ICP) in a rat model of acute mass lesions. We now propose a Phase II effort which includes 1) integration of ESPRIT into a real-time clinical monitoring platform; 2) application of a noise-immune, adaptive strategy to interpret trends in the SEP signal; and 3) evaluation of the technology in a pilot study in the neurocritical care unit. It is our long-term goal to develop a useful tool to assist the neurointensivist in evaluating patients who present with an acute intracranial mass.